This invention relates to hot-melt adhesives based on polyaminoamides and the use thereof for sealing cavities and cracks in soils, in rock formations, building structures and/or walls.
Walling and cavities in soils, rocks or in mines, in particular in building structures, such as tunnels, galleries, shafts, channels and caverns, have to be sealed in order to provide protection from penetration by water or penetration by liquids or gases containing dangerous substances. For this purpose, a liquid sealing materials is introduced under pressure (injected) into the adjoining rock or the adjoining soils via a sealed drilled hole.
Known injection liquids are cement suspensions, solutions or dispersions of polyurethane resins or epoxide resins and liquid multi-component polyurethane resins or epoxide resins. These injection liquids have the disadvantage of very long curing times which cannot be adjusted exactly. In large building structures, such as tunnels, this produces severe technical difficulties, in particular when it leads to so-called “back-flow”, that is when there are cracks, gaps, pores or fissures at the surface of the rock or masonry through which the injection liquids may escape before they have cured. This means that sufficient injection pressure cannot be built up so that the cracks, fissures or cavities are not sufficiently filled which results in defective sealing. Hitherto, in these cases, it has proved helpful to seal the fissures found at the surface with a rapid-setting mortar or to use a particularly rapid-curing injection resin at the escape points. Furthermore, it is difficult to introduce these injection resins in such a way that shrinkage during the curing process does not jeopardise the sealing function. DE-A-19728088 suggests a method for sealing structural parts by injecting gel-forming waterglass solutions in which the waterglass solution is mixed with esters or an aqueous curing solution which contains alkali metal aluminates, salts of alkaline earth metal cations, acidic water-soluble salts, glyoxal or organic acids or compounds thereof, before feeding to the site of injection or when emerging from the site of injection. This converts the waterglass solution into a gel. Although these types of gel-forming systems may be formulated so that gel production takes place very rapidly, they have the critical disadvantage that they do not have a high gap-bridging effect, in particular if these gaps are also intended to be sealed against water which is under pressure.
To overcome these technical difficulties in the processes disclosed hitherto, WO 00/12863 suggests a process for sealing rock or building materials and a device for this in which hot hot-melt adhesives with a low viscosity and rapidly produced initial strength are injected under high pressure into the rock or building material via the drilled hole, whereupon they penetrate into the fissures and pores in the rock or building material to be sealed. After the hot-melt adhesive cools and solidifies, the pores and fissures are sealed and permanently closed up. It is suggested that polyamides or gels with polyamide-like properties are used for this purpose. No data about the composition of the hot-melt adhesives suitable for this purpose are given in this document. In particular, no data at all on ecological compatibility are given.
Starting from the prior art, the inventor has noted the object of providing polyaminoamide hot-melt adhesives which are suitable for the previously mentioned objective of sealing cavities in soils, in rock formations, building structures and/or walls.